Well a good starting point is to google the breed clubs of the breeds you are interested in - they are most likely to point you towards responsible breeders who will have carried out all the necessary health checks.
You could also find out when there are some shows on in your area and even though you may not want to show yourself you can go along and get chatting to some owners - again even if the people who you talk to dont have puppies due they usually know of any litters that are going to be born.
Champdogs - The Pedigree Dog Breeders Website is a good site to research breeders/owners too - use the guided search and its a really good site to browse
